Michael Mayfield was found with a stab wound to his chest around 7:40 p.m. Feb. 11 in the 2100 block of Curtis Street, police said. The 40-year-old Richmond resident was transported to an area hospital, where he died. Already in custody in connection with Mayfield’s murder is 42-year-old Robert Charles Briggs of Berkeley, who has been charged with assault with a deadly weapon and accessory to murder, according to police. Authorities are still looking for another Berkeley man believed to have been involved in Mayfield’s murder, 22-year-old Kevin Aaron Alvarado, police said. Alvarado is an alleged member of the West Side Berkeley gang and should be considered armed and dangerous, according to police.